class_docstr: class for handling plain text corpus
      
docstr: save corpus to files
  
  :param str folder: path to directory
  :type folder: string
docstr_tok: ["save","corpus","to","files",":","param","str","folder",":","path","to","directory",":","type","folder",":","string"]
code: def save(self, folder):
      """save corpus to files
  
      :param str folder: path to directory
      :type folder: string
      """
      try:
          mkdir(folder)
      except Exception:
          pass
      for document in self.documents:
          filename = join(folder, document.id)
          content = "\n".join(document.sentences)
          write(filename, content)
  
file_path: underthesea/underthesea/corpus/plaintext_corpus.py
imports: from underthesea.corpus import Corpus, Document
  from os.path import join
  from os import listdir, mkdir
  from underthesea.feature_engineering.unicode import UnicodeTransformer
  from underthesea.util.file_io import write
  import io
label_desc: Use image node_id 3 for calling the PlainTextCorpus obj's underlying member method code with example usage: obj.save(folder) without return types